State-stabilizing Interactions in Bacterial Mechanosensitive Channel Gating and Adaptation.
Andriy Anishkin1, Sergei Sukharev
1Department of Biology, University of Maryland, College Park, Maryland 20742, USA.
The Journal of Biological Chemistry
|April 23, 2009
Summary
Bacterial mechanosensitive channels MscL and MscS regulate turgor pressure. Their gating mechanisms involve pore-lining helix movements, with hydration limiting pore opening and complex interactions governing MscS channel behavior.
Area of Science:
- Biophysics
- Molecular Biology
- Cell Biology
Background:
- Bacterial mechanosensitive channels (MscL and MscS) are crucial for turgor regulation in bacteria.
- These channels serve as models for understanding membrane protein conformational changes driven by membrane tension.
Purpose of the Study:
- To define the gating principles of bacterial mechanosensitive channels MscL and MscS.
- To compare the structural transitions and functional behaviors of MscL and MscS.
Main Methods:
- Comparative analysis of MscL and MscS structures.
- Prediction of conformational transitions based on structural data.
- Discussion of physical factors influencing channel gating and functional states.
Main Results:
- MscL, a pentamer, opens a large pore at high tensions.
- MscS, a heptamer, shows transient activation of a smaller pore at moderate tensions, leading to inactivation.
- Channel opening is generally facilitated by pore-lining helix tilting and outward movement, with pore hydration as a kinetic barrier.
Conclusions:
- The flexibility of pore-lining helices and interhelical associations are key to MscS's adaptive behavior.
- Physical factors influencing transitions and stabilization of functional states in these channels are discussed.
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